This invention relates to integrated circuit technology, and more particularly to laser programmable integrated circuit technology.
Integrated circuits rely on metal interconnections as a means of linking individual logic components together. It is this combination of logic components that allows the integrated circuit to perform desired functions. One method of programming integrated circuits is masking. Masking entails placing a mask over the integrated circuit containing unconnected logic components and making connectors along the paths exposed in the mask. Typically, this method is employed to connect special purpose logic components designed exclusively to perform a given function. However, it may also be employed to connect general purpose logic modules.
Mask fabrication, however, takes weeks or even months. Furthermore, once a mask is fabricated, it is not easily changed. To customize different integrated circuits, a different mask must be used and, of course, the resulting cost in time must be paid. This delay represents a significant hurdle in minimizing the time required for manufacture. One response has been to utilize an alternate approach not requiring masks.
The alternate approach utilizes arrays of metal interconnections. Under this approach the array acts as a foundation through which the programmed path will be made. Initially, the array is totally unprogrammed. Each path is programmed individually by linking crossing interconnectors and/or breaking interconnectors to produce the desired connections and cuts and ultimately, to produce the desired function.